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DOI: 10.1055/s-2005-919275
Aerobic locomotor exercise modulates brain activation patterns in chronic stroke survivors
In chronically disabled stroke survivors specific rehabilitation therapy can improve motor function and is associated with changes in cortical activation as determined by functional magnetic resonance imaging (Luft et al. JAMA 2004, 292:1853, Schaechter et al. Prog Neurobiol 2004, 73:61). Most rehabilitation therapies target the upper extremity and encourage repeated use of the paretic limb. Locomotor disability – the major burden for chronic stroke survivors in daily live – is more difficult to rehabilitate. We developed a rehabilitation program based on aerobic treadmill exercise training (AEX) for 6 months that was shown to improve gait, hamstring strength, and fitness of stroke patients (Smith et al. Stroke 1999, 30:2112; Macko et al. Arch Phys Med Rehabil 2001, 82:879). Here, we tested the hypothesis that AEX modulates brain activation patterns associated with unilateral knee flexion/extension movements. BOLD-weighted fMRI were acquired in 9 patients undergoing AEX and 9 control patients according to protocols previously described (Luft et al. Neuroimage 2005, in press). Control patients received a dose (time)-matched standardized training regimen consisting of passive stretching exercises.
There were no differences between trained and control patients regarding age, time since stroke, gender, lesion side, and location (classified as cortical, subcortical and brainstem). In trained patients, increased activation was observed in bilateral red nucleus, contralesional primary motor cortex, and supplementary motor area (SMA). In contrast, activation in control patients was reduced in these and other regions of interest (ROI: primary somatosensory cortex, cerebellum, cingulum, Brodmann's areas 6, 7, 40). Beta coefficients of single subject statistical parametric mapping analyses were further analyzed for each ROI. Repeated measures ANOVA revealed significant effects for ROI (F=2.9, p=0.009), group (F=17.8, p<0.0001), time (F=48.42, p<0.0001), and for the interaction group x time (F=6.5, p=0.012). These results demonstrate that AEX therapy leads to specific cortical and subcortical reorganisation of brain regions involved in knee movement. This reorganization may be one mechanism by which AEX improves locomotor function.